Silica-rich carrier, catalyser for heterogeneous reactions and method for the production thereof

ABSTRACT

A silica-rich support is developed, which is used for preparing catalysts and may be employed in other fields of engineering: for producing fiber optic materials, in the manufacture of filters, etc.  
     The support has a specific structure characterized by a set of claimed physicochemical properties: in the  29 Si MAS NMR spectrum the state of silicon is characterized by the presence of lines with chemical shifts−100±3 ppm (line Q 3 ) and −110±3 ppm (line Q 4 ), with the ratio of the integral intensities of the lines Q 3 /Q 4  of from 0.7 to 1.2 (FIG.  1 ); in the IR spectrum there is an absorption band of hydroxyl groups with the wave number 3620-3650 cm −1  and half-width 65-75 cm −1  (FIG.  2 ); the carrier has a specific surface area, as measured by the BET techniques from the thermal desorption of argon, S Ar =0.5-30 m 2 /g and the surface, as measured by alkali titration techniques, S Na =10-250 m 2 /g, with S Na /S Ar =5-30.  
     A catalytic component is incorporated into the bulk of the support with a specific structure, this leading to the providing of highly active catalysts, resistant to sintering and to the effect of contact poisons. The conditions for the incorporation of the catalytic component are: an elevated temperatures and elevated pressures.

FIELD OF THE ART

[0001] The present invention relates to supports for use in variousfields of the art and to catalysts for processes of deep oxidation ofhydrocarbons (neutralization of exhaust gases), hydrogenation(acetylene, nitrobenzene), oxidation of sulfur dioxide (in production ofsulfuric acid), partial oxidation of hydrocarbons (epoxidation ofethylene and propylene), conversion of ammonia (in production of nitricand hydrocyanic acid), etc.

BACKGROUND OF THE INVENTION

[0002] Usually catalysts for these processes are active metals, oxidesor salts deposited on supports that are amorphous or crystalline oxidesof 2, 3, 4 Group elements, for instance, supports based on silica, whichare characterized by high chemical and thermal stability, by thepossibility of controlling within a wide range the specific surface andporous structure thereof, and of making products of various shapes:powders, cylindrical or spherical granules, single- or multi-channelmonoliths, woven and nonwoven materials manufactured from fine fibers.

[0003] The most important functions of the support are the providing ofa highly active state of deposited catalytic components and maximumcomplete utilization of the catalytic properties of these usually costlycomponents.

[0004] This is achieved:

[0005] by maximum dispersion of catalytically active substances and byoptimal distribution thereof over the surface or in the surface layersof the support;

[0006] by the effect produced by the support on the chemical andelectronic state of the catalytic component to increase its performancethereof;

[0007] by increasing the effectiveness factor by using an optimal porousstructure which ensures good mass transfer of substances participatingin the catalytic reaction, and also by employing supports having optimalshapes: rings, multi-channel monoliths, fibrous structures manufacturedin the form of woven and nonwoven materials, wool, cardboard, etc.

[0008] The most widespread method of dispersing a catalytic component isthe use of supports with a high specific surface and a sufficiently highinteraction with an active component, precluding the surface diffusionand growth of the particles of the latter. Different processes have beendeveloped for the synthesis of siliceous supports with a high specificsurface, for instance, hydrolytic precipitation of silica from inorganicand organic silicon compounds, yielding very small particles (R. K.Iler, The Chemistry of Silica, Moscow, Mir Publishers, 1982, vol.1,2,p.1127). However, as a rule, highly dispersed supports are characterizedby a fineporous structure, which leads to reducing the effectivenessfactor due to pore diffusion restrictions.

[0009] Another technique for providing siliceous materials with a highspecific surface is selective acid extraction of non-silica componentsfrom multycomponent silicate materials, e.g., from silica glasses. Theacid-insoluble silica skeleton makes up porous systems with a largespecific surface, so-called porous glasses (S. P.Zhdanov. // ZhurnalVKhO im. Mendeleeva, 1989, vol. 34, No. 3, pp. 298-307). The value ofthe specific surface area, the pore size and volume substantially dependon the conditions of leaching out, as well as on the composition andpre-treatment of starting glasses, which determine the homogeneity ofheteroatoms distribution and the formation of micro-heterogeneous areasunder liquation. As a rule, in leached glasses micro- and mesoporousstructures are formed (R_(pore)<100 Å). Like in conventional supports,the presence of small pores may reduce the effectiveness factor. Theproviding of larger transport pores of the support substantially lowersits mechanical strength, especially when fine-fiberglass materials areused, and therefore special techniques are required in the preparation(U.S. Pat. No. 4,933,307, IPC C03C 11/00, C03C 12/00, 1990).

[0010] In most cases it is preferable to use coarsely sufficientlystrong and nondispersed supports of optimal shapes, but for achievinghigh-activity states of catalytic components thereon it is necessary tocarry out additional modifications of support. For instance, honeycombmonoliths or glass fiber woven materials are used, to whichcomparatively thin layers of highly dispersed oxides are deposited,which are catalysts (U.S. Pat. No. 4038214, IPC B01J 23/86, B01J 23/84,B01J 35/06, 1977) or serve as a support for deposition more valuablecatalytic components, noble metals inclusive (U.S. Pat. No. 5,552,360,IPC B01J 21/04, 21/08, 1996; U.S. Pat. No. 5,155,083, IPC B01J 21/06,B01J 21/08, 1992). However, such techniques complicate the technology ofcatalysts preparation and, correspondingly, make it more expensive.

[0011] Catalytic components deposited on non-modified supports arecharacterized not only by their low initial dispersity, but also byinsufficiently strong binding with the support, which causes highsurface mobility of catalytic substances, leading to their agglomerationduring operation, as well as to peeling off the surface and possibleentrainment by the gas flow even in the case of medium-temperaturecatalytic processes. This was observed, when active metals weredeposited on glass fiber woven supports. In order to eliminate thisdisadvantage, in RU Pat. No. 2069584 (IPC B01J 23/38, 23/70, 1996) forincreasing adhesion of catalytically active metals to the surface of thesupport at the early stages of its synthesis, the composition of thesupport is varied. To do that, dopping additives also from catalyticallyactive metals and/or oxides thereof are incorporated into the supportmanufactured in the form of threads, fibers, woven and nonwovenmaterials from silicon and/or aluminum oxides. Dopping additives areused as a raw materials for preparing melt based on silicon oxide. Thesupport fibers thus made are further subjected to weaving and leachingoperations, and after that a catalytic component is deposited on thesurface of the woven material.

[0012] This process is disadvantageous in a considerable part of metalbeing localized in the bulk of the glass fiber, and, consequently, inineffective utilization thereof in catalysis, as well as in possibletechnological losses of valuable metal at the early stages ofincorporating thereof. It may be supposed that dopping additivesincorporated at the early stages into the bulk of the glass supportcause a change in the support structure and assist in the formation ofcertain structures which are responsible for catalyst performance.

[0013] One of the types of structures of a silica-rich support,providing the formation of highly active catalytic species, is proposedin the present invention.

DISCLOSURE OF THE INVENTION

[0014] The object of the proposed invention is to provide silica-richcatalysts comprising a catalytic component in a highly active state,owing to employing the proposed silica-rich support with a specificstructure, characterized by a set of claimed physicochemical propertiesand owing to a method of incorporating into this structure a catalyticcomponent which ensures a predominant distribution thereof in the subsurface layers of the support in a highly dispersed active stateresistant to sintering, agglomeration of catalytic components, to theirpeeling off the support, and to the effect of contact poisons.

[0015] Said object is accomplished by that for preparing catalysts it isproposed to use a silica-rich support comprising silicon oxide andnonsilica-containing oxides, for instance, aluminum oxide, sodium oxide,and the like, characterized by a set of the following physicochemicalproperties:

[0016] in the ²⁹Si MAS NMR (nuclear magnetic resonance) spectrum thestate of silicon in the support is characterized by the presence oflines with chemical shifts −100±3 ppm (line Q³) and −110±3 ppm (lineQ⁴), with the ratio of the integral intensities of the lines Q³/Q⁴ from0.7 to 1.2;

[0017] in the IR (infrared) spectrum there is an absorption band ofhydroxyl groups (OH groups) with the wave number of 3620-3650 cm⁻¹ andhalf-width of 65-75 cm⁻¹ the content of hydroxyl groups in the matrix ofthe support ranging from one hydroxyl group per atom of silicon to onehydroxyl group per 2 atoms of silicon (OH/Si=1-0.5);

[0018] the support has a specific surface, as measured by the BETtechniques from the thermal desorption of argon, S_(Ar)=0.5-30 m²/g andthe surface, as measured by alkali titration techniques, S_(Na)=10-250m²/g, with S_(Na)/S_(Ar)=5-30.

[0019] The combination of features claimed by us define the presence inthe silica support of specific structures capable of ensuring a highlyactive state of the catalytic component, provided that the claimedconditions of incorporating thereof are observed.

[0020] In the ²⁹Si MAS NMR spectrum of the claimed support lines arepresent with chemical shifts −100±3 ppm (line Q³) and −110±3 ppm (lineQ⁴ in FIG. 1, Samples 1, 2), with the ratio of the integral intensitiesof the lines Q³/Q⁴ of from 0.7 to 1.2, which, according to literaturedata (Mastikhin, V. M., Lapina O. B., and Mudrakovsky I. L., NuclearMagnetic Resonance in Heterogeneous Catalysis, Novosibirsk, Nauka, 1992,224 pp.; Engelhardt G. and Michel D., High-Resolution Solid-State NMR ofSilicates and Zeolites, John Wiley @ Sons, 1987, 486 pp.), characterizethe following structural states of silicon in silicate compounds. LineQ⁴ pertains to silicon atoms in the tetrahedral oxygen environment, inwhose second coordination sphere all the 4 atoms are silicon atoms, thiscorresponding to three-dimensional polymeric fragments fromsilicon-oxygen tetrahedra bonded by siloxane bonds. It is exactly suchstates that are realized inside monolithic globules of conventionalsilica, wherein polymerized silicon-oxygen tetrahedra make up acontinuous three-dimensional network.

[0021] The line Q³ at low content of cations of Groups 1, 2 correspondsonly to silicon-oxygen tetrahedra with one OH group in the firstcoordination sphere. A specific feature of the claimed structures is ahigh Q³/Q⁴ ratio of 0.7 to 1.2, at which the content of hydroxyl groups(OH groups) ranges from one hydroxyl group per silicon atom to onehydroxyl group per two silicon atoms. Similar amounts of OH groups aredetermined by infrared spectroscopy techniques Structures with suchQ³/Q⁴ ratio (with other claimed features being present) may be describedby a layered model, in which thin layers of 3-4 silicon-oxygentetrahedra are separated by narrow interlayer spaces. At the interfacesilanol groups SiOH are located (Q³ states).

[0022] The herein-claimed feature of the silica-rich support beingprotected and of a catalyst—an absorption band of hydroxyl groups with awavenumber of 3620-3650 cm⁻¹ and half-width of 65-75 cm⁻¹ in the IRspectrum of the silica-rich support (FIG. 2, Samples 1, 2) is indicativeof a large number of OH groups being in a geometrically constrainedconditions, i.e., it confirms the presence of narrow interlayer spacesof the above-described structure.

[0023] Catalytically active components (in the form of metal cations)incorporated into interlayer spaces are subjected to a strong chemicaleffect of the described silica-rich support matrix, and under thiseffect of the support they must reveal high catalytic activity. However,diffusion restrictions may retard the incorporation of cations into theinterlayer spaces and their chemisorption in the support. An increase inthe insertion of catalytic components into the described support havingthe claimed structure is possible upon separation of the layers ofsilicon-oxygen fragments, if the layers are sufficiently thin (thisbeing characteristic of high Q³/Q⁴ ratios) and a large number of OHgroups are found in the interlayer space (this being evidenced by NMRand IR spectroscopy data), whose protons are capable of cation exchange(3620-3650 cm⁻¹ absorption band).

[0024] The ability of support with a comparatively low surface area(S_(Ar)=0.5-30 m²/g) to chemisorb cations is reflected by the thirdfeature claimed by us: the magnitude of the surface area, determinedfrom the chemisorption of sodium cations (S_(Na)), is 10-250 m²/g (themethod of Sears, 1. G. W. Sears //Anal. Chem., 1956, vol. 28, p. 1981;2. R. Iler, The Chemistry of Silica, Moscow, Mir Publishers, 1982, vol.2, p. 480) at the ratio of S_(Na) to the magnitude of the specificsurface, as determined by the BET techniques from the adsorption ofargon (S_(Na)/S_(Ar)=5-30). We would like to note also that the lowspecific surface, as determined by the BET techniques at a high fractionof Q³ and a high concentration of OH groups, confirms the specificstructure of the support, which may be described most adequately by alayered structure model: thin layers of silicon-oxygen tetrahedra occurintermittently with narrow spaces, wherein a large number of hydroxylgroups are localized, which under definite synthesis conditions arecapable of ion exchange for the cations of catalytic components.

[0025] The claimed silica-rich support may comprise at least one ofmetals and/or oxides of Groups I and II of the Periodic System of theElements in an amount of not over 1 percent by weight for improving theconditions of incorporating the catalytic component into the supporthaving the claimed structure.

[0026] The proposed support may be prepared from various silicatematerials and have the form of fibers, woven and nonwoven materials,cylindrical and spherical granules, single- and multi-channel tubes.

[0027] The claimed structures may be synthesized in various ways, forinstance, with silicate materials being leached by using acid solutions,with varying the composition and structure of silicate materials, andalso with varying the nature and concentration of the acid employed, theleaching and subsequent heat-treatment conditions in such a manner as toproduce a structure with the claimed properties. Important conditions offorming the above-described structures are as follows:

[0028] a) homogeneous distribution of heterocations in the bulk of thestarting silicon-containing material;

[0029] b) absence of coalescence of the spaces when extracting cationsand/or in the course of subsequent chemical and heat treatments, thisbeing achieved by using special techniques in the synthesis: applying ofultrasonic or magnetic fields, optimization of the temperature andcomposition of the liquid and gaseous medium in the leaching andsubsequent heat treatment, carrying out liquid-phase operations in thepneumatic pulsed mode or with using of magnetic and ultrasonic fields.

[0030] The support after leaching contains preferably from 60 to 99.9percent by weight of silicon oxide, the balance being componentsconventional for silicate glass compositions: oxides of aluminium,magnesium, calcium, boron, etc., the amount of silica in the claimedsupport being preferably more than 70 percent by weight.

[0031] Hence, in the proposed support the combination of the claimedfeatures testifies to the presence of specific loosened, pseudo-layeredstructures, into which catalytic components in non-equilibrium highlydispersed, and, consequently, highly active state can be incorporatedand stabilized therein. We would like to note that in the silica-richmaterials known to us—silica gels (FIG. 1, Sample 4) and in silicateglasses (FIGS. 1, 2, Sample 3)—structures with the combination of thephysicochemical characteristics claimed by us are absent.

[0032] The proposed support is used for preparing various catalysts forheterogeneous reactions and may have any geometric forms: fibers, wovenand nonwoven materials, cylindrical and spherical granules, single- andmulti-channel tubes.

[0033] Using a catalytic component from the group comprising platinum,rhodium, iridium, silver, zirconium, chromium, cobalt, nickel,manganese, copper, tin, gold, titanium, iron, molybdenum and/or theiroxides in an amount not exceeding 2 percent by weight (based on metal),we have obtained catalysts with an activity exceeding the activity ofheretofore-known catalysts.

[0034] As an active component it is preferable to use platinum groupmetals, which makes it possible to prepare highly active catalysts witha small amount of the active component.

[0035] Basing on the claimed support, we propose a range of highlyeffective silica-rich catalysts containing as catalytic components asmall amount of metals and/or their oxides, very promising for use inmany chemical processes (oxidation of methane, propane, butane, ammonia,sulfur dioxide; hydrogenation of vegetable oils; hydrogenation ofaromatic compounds), wherein they display a higher activity than theknown catalysts.

[0036] The proposed catalysts which contain as the active component atleast one metal selected from the group comprising platinum, palladium,manganese, nickel, cobalt, chromium and/or oxides thereof in an amountof 0.01-1.5 percent by weight have a high activity in the process ofdeep oxidation of hydrocarbons.

[0037] The catalyst containing as the active compound at least one ofplatinum group metals and/or their oxides in an amount of 0.05-1.0percent by weight (based on metal) demonstrates a high degree ofconversion of sulfur dioxide to sulfur trioxide.

[0038] For alkylation of hydrocarbons, a catalyst is used, whichcontains zirconium in an amount of up to 2 percent by weight (based onmetal).

[0039] The catalytic component is located in the sub surface layers ofthe support having the claimed structure. Additional incorporation intothe catalyst of at least one compound of an element selected from Groups1, 2, 3, 4 of the Periodic System of the Elements in an amount notexceeding 1.5% contributes to incorporating, stronger fixing andstabilizing the component in the support.

[0040] For producing catalysts with the use of the proposed support, itis necessary to meet definite optimal conditions of incorporatingcompounds of the catalytic compounds, leading to their localization inthe claimed specific loosened, pseudo-layered structures and tostabilization of catalytic components in highly active state.

[0041] Such conditions for incorporating the catalytic component intothe support structures are: using an elevated temperature from 40 to200° C., elevated pressure of 1 to 200 atmospheres (superatmosphericpressure), using solutions of compounds of catalytic compounds, having adefinite pH value (preferably 2-10), additionally incorporating into thesupport compounds of an element selected from Groups 1, 2, 3, 4 of thePeriodic System of the Elements, simultaneously with, prior to, or aftercontacting the support with a solution of compounds of the catalyticcomponent.

[0042] Elevated temperature and pressure increase the mobility of layerswith respect to one another, thereby favoring their being moved awayfrom one another and the penetration of catalytic components into thesub surface interlayer space of the support. Elevated temperatureincreases the diffusion of the catalytic component and intensifies theion exchange of the protons of hydroxyl groups, found in the spaces, forthe cations of the catalytic component. Compounds of Group 1, 2, 3, 4elements, additionally incorporated into the support may play the roleof “pillars” in the interlayer spaces, facilitating the incorporation ofcatalytic components (pillaring effects).

[0043] After contacting the support with the impregnating solution ofcatalytic component, the sumple is washed out with a 3-10-fold excess ofwater with pH 3-8 to remove catalytic component compounds weakly boundwith the support surface. Then drying and heat treatment are carried outat temperatures of 100-800° C. in a gas medium or in vacuum of down to10 ⁻⁴ mm Hg.

[0044] So, the use of the silica-rich support with the claimed specificstructure and of the claimed process for preparing catalysts forheterogeneous reactions ensures the preparation of catalysts with a highactivity, resistance to sintering, agglomeration of catalyticcomponents, to their peeling off the support, and to the effect ofcontact poisons.

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In FIGS. 1, 2 and in Table 1 the properties of the claimedsilica-rich supports (Samples 1, 2) and of the known supports (Samples3, 4) are presented.

[0046]FIG. 1 shows ²⁹Si MAS NMR spectra (MAS stands for “magic anglespinning”). The spectra were recorded on “Bruker” MSL-400 pulsed NMRFourier spectrometer (Germany) (magnetic field 9.4T). Magic anglespinning of the samples was carried out with the help of a high-speeddevice manufactured by the firm Asp-Rotor-Consult (Denmark), in rotorsfrom silicon nitride and zirconium oxide, with the rotation frequency of8-10 thousand Herz (FIG. 1). The ²⁹Si MAS NMR spectra were recordedunder the following conditions:

[0047] Nuclear spin 1/2

[0048] Isotope content 4.7%

[0049] Resonance frequency 79.49 MHz

[0050] Sweep 30 kHz

[0051] Pulse duration 4μ is

[0052] Pulse-to-pulse delay 20 s

[0053] Number of scans 300-2000

[0054] Standard—tetramethoxysilane (TMS)

[0055] The clear position of the lines enables one to evaluate withsufficient accuracy (±15%) the fractions of different structural statesof silicon (Q³ and Q⁴) by denonvolution of the experimental spectrum bymeans of computer simulation, shown in FIG. 1 for Sample 1.

[0056] Samples 1 and 2 pertain to the claimed supports, and in the ²⁹SiMAS NMR spectrum they have lines with chemical shifts −100±3 ppm (Q³)and −110±3 ppm (Q⁴).

[0057] Sample 3 pertains to the support described in the prior art: inRU Pat. No. 2069584. Sample 3 is prepared in the following manner.Platinum chloride is added to the glass components in an amount that thecontent of platinum chloride in the final product should be 0.1%.

[0058] The resulting silicate glass fiber cloth support is leached in a10-17% H₂SO₄ at 93-98° C. and then washed out. After drying the heattreatment are carried out at 650° C.

[0059] In the ²⁹Si MAS NMR spectrum of Sample 3 the line Q⁴ with thechemical shift −110±3 ppm is predominantly present: the integralintensity of the line Q⁴ is 97%, while the integral intensity of theline Q³ is ˜3% (Table 1), i.e., the ratio Q³/Q⁴=0.03, whereas Samples 1and 2 are characterized by the high ratio Q³/Q⁴=0.7-0.9.

[0060] Sample 4 is produced in the following manner.

[0061] A support is prepared by leaching silica, whose composition is97% SiO₂, 2.4% Na₂O, 0.6% Al₂O₃ and which is calcined at 1200° C., theresulting product is treated with HNO₃ at 90° C. and washed out withwater to pH 6.5-7.0. Then heat treatment is carried out in a stream ofair at 250° C. for 10 hours.

[0062] This Sample 4, similarly to Sample 3, is characterized in the²⁹Si MAS NMR spectrum by the low ratio Q³/Q⁴.

[0063]FIG. 2 shows the IR spectra of silica-rich supports.

[0064] The IR spectra were recorded at room temperature withoutpretreatments on a modernized IFS-113v (Bruker) spectrometer in therange of 1100-7000 cm⁻¹ with resolution of 4 cm⁻¹. The intensity wasevaluated in units of optical density referenced to the weight of thesample per cm² of the beam cross-section. The concentrations of OHgroups (C, μmole.g) were measured, proceeding from the intensity of thebands of stretching vibrations of OH groups in accordance with theformula C=A/(A_(op)) (E. A. Paukshtis and E. N. Yurchenko //UspekhiKhimii, 1983, vol. 52, Issue 3, p. 426), where ρ (g/cm²) is twice theamount of the catalyst per cm² of the beam cross-section, since thelight passes through the sample twice: before and after the reflectionfrom the mirror; A (cm⁻¹) is the observed integral absorption for theband being analyzed; A_(o) (cm/μmole) is the integral absorptioncoefficient which in accordance with (I. B. Peri //J. Phys. Chem., 1966,vol. 70, p. 29) for different bands was taken to be equal to:

A_(o), cm/μmole 3 5 22 25

[0065] Absorption band, cm⁻¹ 3737-3740 3620-3650 3400 3300

[0066] The accuracy of evaluating the concentration of OH groups was±30%.

[0067] In the spectra of Samples 1, 2 pertinent to the claimed supportthere is an absorption band of OH groups with the wave number 3620-3650cm⁻¹ and half-width 65-75 cm⁻¹.

[0068] Sample 3 is pertinent to the known solution according to RU Pat.No. 2069584. In the infrared spectrum of this Sample there is no band ofabsorption of OH groups with the wave number 3620-3650 cm⁻¹ andhalf-width 65-75 cm⁻¹.

The Best Variant of Carrying out the Invention

[0069] A support having the claimed structures is formed upon leachingsilicate glass materials manufactured in the form of granules, fibers,woven and nonwoven products therefrom. The leaching conditions and thestarting silicon-containing material are so selected as to obtain asupport having the required claimed structure.

[0070] For producing catalysts, solutions of compounds of activeelements with pH=2-10 are prepared. If necessary, elements of Groups 1,2, 3, 4 of the Periodic System of the Elements are introduced into theimpregnating solution in an amount of 1.5 percent by weight. Theseelements may be contained in the support before impregnating it withactive elements.

[0071] The impregnation is carried out at a temperature of 40-200° C.and superatmospheric pressure of 1-200 atmospheres. After contacting thecarrier with the impregnating solution, if necessary, the catalyst iswashed out with a 3-10-fold excess of water with pH=3-8 to remove activecomponent compounds weakly bound with the support. Then heat treatmentis carried out at a temperature of 100-800°C. in a gas medium atatmospheric pressure or in vacuum of down to 10⁻¹ mm Hg. The heattreatment conditions are selected in conformity with the requirements tobe met by the catalyst, depending on the reaction in which the catalystwill be tested.

[0072] The proposed silica-rich support has unique physicochemicalproperties. Thereby an opportunity is provided to achieve highefficiency and selectivity of catalytic processes, the catalysts arenoted for enhanced chemical and thermal stability and higher strengthcharacteristics. The catalysts have a high activity at a very lowcontent of the catalytic component.

[0073] The catalysts prepared in accordance with the claimed process aretested in the process of deep oxidation in excess oxygen on modelmixtures containing n-butane, propane and carbon oxide.

[0074] Tests in the reactions of deep oxidation of n-butane and carbonoxide are carried out under similar conditions on a flow-circulationinstallation at atmospheric pressure, the same space velocity ofsupplying the gas-and-air mixture.

[0075] The measure of the catalyst activity in the reaction of n-butaneoxidation is adopted to be the rate of the n-butane oxidation reaction(cm³ of C₄H₁₀/·g.s. ·10 ⁻²) at the temperature of 400° C. A higher rateof the reaction of deep oxidation of butane corresponds to a more activecatalyst.

[0076] The measure of the catalyst activity in the reaction of oxidationof carbon oxide is adopted to be the temperature at which the degree ofoxidation of carbon oxide is 85%. The lower the temperature at which the85% oxidation of carbon oxide is reached, the higher the catalystactivity is.

[0077] Tests in the reaction of deep oxidation of propane are carriedout in an isothermal flow reactor. The measure of the catalytic activityis adopted to be the degree of conversion at a definite temperature.

[0078] The catalytic activity in the reaction of oxidizing SO₂ into SO₃is measured on a flow-type installation by following a standardprocedure most widespread in the Russian practice for assessing thequality of industrial catalysts (G. K. Boreskov, Catalysis in SulfuricAcid Production, Moscow, Goskhimizdat, 1954, p. 87). The test is carriedout by the flow method with the composition of the gas mixture: 10 vol.% SO₂, 18.9 vol. % O₂, 71.1 vol. % N₂; at the temperature of 485° C., ata space velocity of gas providing a constant contact time τ=0.9 sec. TheSO₂ concentration is measured at the inlet to and at the outlet thecatalyst bed, and the degree of SO₂ conversion (X_(int).)is assessedfrom the change of said concentrations, this being the measure ofactivity of the initial catalyst under the selected standard conditions.

[0079] The catalyst thermostability is determined by following theprocedure of accelerated thermal aging (G. K. Boreskov, Catalysis inSulfuric Acid Production, Moscow, Goskhimizdat, 1954, p. 153). Accordingto this procedure, first the initial activity of the catalyst at 485° C.is determined (X_(int).), then the temperature is raised to 700° C. andthe catalyst is maintained at this temperature for 50 hours. After thatthe temperature in the flow reactor is lowered to 485° C., and at thistemperature the residual activity of the sample (X_(resid).) ismeasured.

[0080] Besides, for evaluation of the thermal stability, the activity ismeasured at 700° C. on a highly concentrated feed gas: 20 vol. % SO₂, 20vol. % O₂, and 60 vol. % N₂. The measure of the catalysts activity isadopted to be the contact time (τ, sec.) necessary for attaining acertain constant degree of conversion X_(const), away from the reactionequilibrium. Since under the above-indicated test conditions theequilibrium degree of conversion is X_(eq.) ˜51%, for comparing theactivities we have chosen a constant X_(const)=39%. Initial contacttimes τ_(init). and the contact times after testing at 700° C. for 50hours τ_(final) were measured. Small τ values and their constancy duringprolonged tests at 700° C. testify to the high activity andthermostability of the catalysts.

[0081] The catalysts are tested in the reaction of ammonia oxidation tonitrogen oxides, in the reaction of selective reduction of nitrogenoxides with methane, in the reaction of alkylation isobutane withbutylene.

[0082] The data on the composition and properties of the support arepresented in Table 1, in FIGS. 1, 2, Samples 1, 2.

[0083] The data on the composition of the catalysts are presented inTable 2.

[0084] The data of tests are presented in Tables 3-7.

[0085] For a better understanding of the present invention, thefollowing particular examples are presented.

[0086] Preparing the Carrier

Sample No. 1

[0087] For preparing the support, unleached sodium silicate glass clothis used, having the composition: 70% SiO₂, 20% Na₂O, 6% A_(2 O) ₃, thebalance being H_(2 O) ₂.

[0088] The glass cloth is treated for 2 hours with a solution having thecomposition 5% NH₃+5% H₂O₂ in the mode of pneumatic pulsating mixing ata pressure of 0.06 MPa, pulsation frequency of 1.5 Hz, pulsationamplitude of 150 mm and washed with water at pH=5.5-7.0. Then the clothis treated with 5% HCl for 3 minutes, then at the temperature of 40° C.for 120 minutes, washed out with water till the washwater pH of 5.5-7.0,and then calcined at the temperature of 200° C. for 12 hours.

Sample No. 2

[0089] Glass cloth of the same composition as in Sample No. 1 iscalcined at 330±20° C. for 2 hours, then treated with 7.5% HNO₃ at 90°C. for 60 minutes, washed out with water till pH=6.5-7.0, then heattreatment is carried out in a stream of air at 350° C. for 12 hours.

[0090] The catalysts exemplified hereinbelow are prepared using asupport with optimal claimed characteristics (Sample No. 1, 2).

EXAMPLE 1

[0091] The support (Sample No. 1, Table 1) is contacted with a solutionof tetrammineplatinum (II) chloride [Pt(NH₃)₄]Cl₂ at 120° C. and atsuperatmospheric pressure of 2 atmospheres. The reagents are taken inamounts sufficient for obtaining the calculated weight concentrations ofmetals in the support, then the cloth is washed out with water to removethe metal compounds weakly bound with the support, dried at 110° C.,calcined in air at 300° C. for 2 hours, and reduced in a stream ofhydrogen at 300° C. for 2 hours.

EXAMPLE 2

[0092] For preparing the catalyst, the support with the characteristicsof Sample No. 2 is used (Table 1).

[0093] Before contacting the support with an aqueous solution ofH₂PtCl₆, cesium cation in an amount of 0.2 percent by weight is insertedinto the support from a CsCl water solution.

[0094] The incorporation of platinum is carried out at the temperatureof 200° C. and superatmospheric pressure of 10 atmospheres in an acidicmedium. Then the catalyst is prepared as described in Example 1.

EXAMPLE 3

[0095] The catalyst is prepared as in Example 2, the difference being inthat ammine complex of palladium is used as the solution of thecatalytic component and no additional cation is introduced into thecatalyst.

EXAMPLE 4

[0096] The catalyst is prepared as in Example 1, the difference being inthat as the catalytic component palladium is incorporated from aPdCl₂+HCl+CsCl solution, and the additional cesium cation is introducedinto the support simultaneously with the catalytic component compound.

EXAMPLE 5-14

[0097] Catalysts are prepared as in Example 1, the difference being inthe compounds of the catalytic components being incorporated, in theiramounts, and in the conditions of contacting the support therewith. Thedata are presented in Table 2.

Industrial Applicability

[0098] The proposed support may be used in chemical industry forpreparing various catalysts for heterogeneous reactions, as well as inmost diverse fields of engineering: in making inorganic membranes, inchromatographic columns, for producing fiber optic materials, in themanufacture of filters, etc. ²⁹Si MAS NMR spectrum data Composition of(FIG. 1) support Ratio of Presence of 3620-3650 Other Integral intensityof Integral intensity of chemical shift cm⁻¹ absorption band components,chemical shift line chemical shift line lines Q³/Q⁴ in IR spectrumS_(Ar), S_(Na), S_(Na) / Nos. SiO₂ wt. % wt. % Q³ −100 ppm ± 3, % Q⁴−110 ppm ± 3, % intensities (FIG. 2) m²/g m²/g S_(Ar) 1 96.5 Al₂O₃, 3.447 53 0.9 + 1.2 23 19 Na₂O, 0.1 2 ″ Al₂O₃, 3.4 41 53 0.7 + 1.5 16 10.1Na₂O, 0.1 3* ″ Al₂O₃, 3.4  3 97 0.03 − 1.2 3.8 3.2 Na₂O, 0.1 4* 99.6Na₂O, 0.1 10 90 0.11 − 10 10 1 Al₂O₃, 0.3

[0099] Composition of catalysts and conditions for their preparation No.of sup- T ° C. of catalytic port sample component Additional Group 1, 2,3, Washing (“+” - T ° C. of heat Nos. From Tab. 1 Catalytic component,wt. % incorporation P, atm* pH 4 element, wt. % yes, “−” - no) treatment1 1 Pt, 0.01 120 2 7 — + 300 2 2 Pt, 0.02 200 10 2 Cs, 0.2 + 200 PH-3 32 Pd, 0.01 150 3 10  — + 350 4 1 Pd, 0 1 200 4 3 Cs, 0.01 + 200 5 2 Mn,1.5 100 1.3 7 K, 0.1 + 300 Au, 0.01 6 1 Ni, 0.5 100 1.3 4 Mg, 1 − 300Co, 0.5 7 2 Cu, 1.0  40 1 7 Ca, 0.5 200 Cr, 0.5 8 1 AG, 0.05 100 30 6Si, 1.5 + 300 Ir, 0.01 9 2 Zr, 1 7 110 1.1 7 — − 200 Fe, 0 3 10 1 Ni,0.5  50 1.0 7 Ca, 0.1 + 900 Pd, 0.1 Sn, 0.1 11 2 Mo, 0.5 150 200 7 — +300 Pt, 0.1 PH = 8 Rh, 0.001

[0100] Results of testing catalysts in the reaction of deep oxidation ofhydrocarbons Oxidation of propane Oxidation of carbon oxide Oxidation ofn-butane Flow method Flow method Catalyst No. Flow-circulation methodDegree of Degree of conversion, (see TABLE 2 Reaction rate, W 10², cm³/g· s conversion, X, % T_(reaction), ° C. X, % T_(reaction), ° C. 1 9.02 —— 95 225 2 9.38 — 95 220 ′3 8.72 91 345 95 170 98 410 4 6.93 — 95 190 55.49 — 85 260 6 6.45 — 85 315 7 8.91 92.5 430 85 280 98 500

[0101] TABLE 4 Tests of catalysts in the reaction of SO₂ oxidation toSO₃ Activity Degree of conversion X, %, under standard test conditionsContact time t, sec. at Catalyst 485° C., 10% SO₂, 18.9% O₂, 700° C.,20% SO₂; 20% O₂, 60% No. (see 71.1% N₂, τ ˜ 0.9 sec. N₂, X_(const.) =39% TABLE 2) X_(init.) X_(resid.) τ_(init.) τ_(final) 1 92.2 91.5 0.350.36 2 90.7 90.1 0.37 0.37 3 91.2 91.0 0.34 0.35

[0102] TABLE 5 Results of testing catalysts in the reaction ofalkylation of isobutane with n-butylene Testing in an autoclaveinstallation, T = 40° C., P = 10 atm. Yield of C₅ Selectivity CatalystNo. fraction on for (see TABLE Reaction Conversion, converted trimethyl2) components % olefins, % pentanes, % 9 isobutane/n- 95.6 81 45butylene 1:25

[0103] TABLE 6 Results of testing catalysts in the oxidation of ammoniato nitrogen(II) oxide Conditions: flow reactor; contact time is 3-5 ·10⁻³ sec. Linear velocity, 1.8-2 m/sec, P is 7 atm. Initial Selectivityfor Catalyst No. concentration of Conversion of nitrogen(II) (see TABLE2) ammonia, vol. % ammonia, % oxide, % 11 7 >98 94

[0104] TABLE 7 Results of testing catalysts in the reaction of selectivereduction of nitrogen oxides with methane Test conditions: T = 250-750°C.; space velocity, h⁻¹: 20000 Concentration of components in CatalystNo. initial mixture, Degree of (see TABLE 2) CH₄:O₂ ratio vol. %purification, % 10 0.55 Nitrogen oxides, 99 0.18 Methane, 1.48 Oxygen,2.60 Argon, the balance

1. A silica-rich support comprising silicon oxide andnon-silica-containing oxides, for instance, aluminum oxide, sodium oxideand others, characterized in that in the ²⁹Si MAS NMR spectrum the stateof silicon in the support is characterized by the presence of lines withchemical shifts −100±3 ppm (line Q³) and −110±3 ppm (line Q⁴), with theratio of the integral intensities of the lines Q³/Q⁴ of from 0.7 to 1.2,in the infrared spectrum there is an absorption band of hydroxyl groupswith the wave number 3620-3650 cm⁻¹ and half-width 65-75 cm⁻¹, and thesilica-rich support has a specific surface area, as measured by the BETtechniques from the thermal desorption of argon, S_(Ar)=0.5-30 m²/g andthe surface, as measured by alkali titration techniques, S_(Na)=10-250m²/g, with S_(Na)/S_(Ar)=5-30:
 2. A silica-rich support according toclaim 1, characterized in that the content of hydroxyl groups (OHgroups) is in the range of from one hydroxyl group per silicon atom toone hydroxyl group per 2 silicon atoms (OH/Si=1-0.5).
 3. A silica-richsupport according to claim 1, characterized in that the amount ofsilicon oxide in the support is 60-99.9 percent by weight.
 4. Asilica-rich support according to claim 1, characterized in that theamount of silicon oxide in the support is preferably more than 70percent by weight.
 5. A silica-rich support according to claim 1,characterized in that it contains at least one of metals of Groups I andII of the Periodic System of the Elements and/or oxides in an amount notexceeding 1 percent by weight.
 6. A silica-rich support according toclaim 1, characterized in that it has the form of fibers, woven andnonwoven materials, cylindrical and spherical granules, single- andmulti-channel tubes.
 7. A catalyst for heterogeneous reactions, forinstance, for deep oxidation of hydrocarbons, partial oxidation ofhydrocarbons, alkylation of hydrocarbons, oxidation of sulfur dioxide,hydrogenation of hydrocarbons, conversion of ammonia, comprising acatalytic component in a silica-rich support comprising silicon oxideand non-silicon-containing oxides, for instance, aluminum oxide, sodiumoxide, and others, characterized in that for preparing the catalyst acarrier is used, wherein the state of silicon in the ²⁹Si MAS NMRspectrum is characterized by the presence of lines with chemical shifts−100␣3 ppm (line Q³) and −110±3 ppm (line Q⁴), with the ratio of theintegral intensities of the lines Q³/Q⁴ of from 0.7 to 1.2, in theinfrared spectrum there is an absorption band of hydroxyl groups withthe wave number 3620-3650 cm⁻¹ and half-width 65-75 cm⁻¹, and thesupport has a specific surface area, as measured by the BET techniquesfrom the thermal desorption of argon, S_(Ar)=0.5-30 m²/g and thesurface, as measured by alkali titration techniques, S_(Na)=10-250 m²/g,with S_(Na)/S_(Ar)=5-30.
 8. A catalyst for heterogeneous reactionsaccording to claim 7, characterized in that the support has the form offibers, woven and nonwoven materials, cylindrical and sphericalgranules, single- and multi-channel tubes.
 9. A catalyst forheterogeneous reactions according to claim 7, characterized in that asthe catalytic component it contains at least one metal selected from thegroup comprising platinum, palladium, rhodium, iridium, silver,zirconium, chromium, cobalt, nickel, manganese, copper, tin, gold,titanium, iron, molybdenum, and/or oxides thereof in an amount notexceeding 2 percent by weight (based on metal).
 10. A catalyst forheterogeneous reactions according to claim 7, characterized in that itadditionally contains at least one metal or oxide selected from Group 1,2, 3, 4 of the Periodic System of the Elements in an amount notexceeding 1.5 percent by weight (based on metal).
 11. A catalyst fordeep oxidation of hydrocarbons according to claim 7, characterized inthat as the catalytic component it contains at least one metal selectedfrom the group comprising platinum, palladium, manganese, nickel,cobalt, copper, chromium and/or oxides thereof in an amount of 0.01-1.5percent by weight (based on metal).
 12. A catalyst for the oxidation ofsulfur dioxide into sulfur trioxide according to claim 7, characterizedin that as the catalytic component it contains at least one of platinumgroup metals or oxides thereof in an amount of 0.05-1.0 percent byweight (based on metal).
 13. A catalyst for the alkylation ofhydrocarbons according to claim 7, characterized in that as thecatalytic component it contains zirconium compounds in an amount of upto 2 percent by weight (based on metal).
 14. A process for thepreparation of a catalyst for heterogeneous reactions, for instance, fordeep oxidation of hydrocarbons, partial oxidation of hydrocarbons,alkylation of hydrocarbons, oxidation of sulfur dioxide, hydrogenationof hydrocarbons, conversion of ammonia, by incorporating compounds ofcatalytic components into a silica-rich support comprising silicon oxideand non-silica-containing oxides, for instance, aluminum oxide, sodiumoxide, and others, drying and subsequent heat treatment, characterizedin that for the preparation of the catalyst a support is used, whereinthe state of silicon in the ²⁹Si MAS NMR spectrum is characterized bythe presence of lines with chemical shifts −100±3 ppm (line Q³) and−110±3 ppm (line Q⁴), with the ratio of the integral intensities of thelines Q³/Q⁴ of from 0.7 to 1.2, in the infrared spectrum there is anabsorption band of hydroxyl groups with the wave number 3620-3650 cm⁻¹and half-width 65-75 cm^(±1), and the support has a specific surfacearea, as measured by the BET techniques from the thermal desorption ofargon, S_(Ar)=0.5-30 m²/g and the surface, as measured by alkalititration techniques, S_(Na)=10-250 m²/g, with S_(Na)/S_(Ar)=5-30, intowhich a catalytic component is incorporated upon contact of the supportwith solutions of compounds of catalytic components at a temperature of40-200° C. and superatmospheric pressure of 1-200 atmospheres.
 15. Aprocess for the preparation of a catalyst for heterogeneous reactionsaccording to claim 14, characterized in that solutions of compounds ofcatalytic components have pH 2-10.
 16. A process for the preparation ofa catalyst for heterogeneous reactions according to claim 14,characterized in that the impregnating solution of a compound of acatalytic components additionally contains at least one compound of anelement of Group 1, 2, 3, 4 of the Periodic System of the Elements in anamount not exceeding 1.5 percent by weight.
 17. A process for thepreparation of a catalyst for heterogeneous reactions according to claim14, characterized in that for the preparation of the catalyst a supportis used, which, before contacting thereof with a solution of a compoundof a catalytic component, is impregnated with at least one compound ofan element from Group 1, 2, 3, 4 of the Periodic System of the Elementsin an amount not exceeding 1.5 percent by weight.
 18. A process for thepreparation of a catalyst for heterogeneous reactions according to claim14, characterized in that after contacting the support with a solutionof a compound of a catalytic component an impregnation is carried outwith at least one compound of an element from Group 1, 2, 3, 4 of thePeriodic System of the Elements in an amount not exceeding 1.5 percentby weight.
 19. A process for the preparation of a catalyst forheterogeneous reactions according to claim 14, characterized in thatafter contacting the support with an impregnating solution of compoundsof catalytic components the catalyst is washed out with a 3-10-foldexcess of water with pH 3-8.
 20. A process for the preparation of acatalyst for heterogeneous reactions according to claim 14,characterized in that heat treatment is carried out at temperatures of100-800° C. in a gaseous medium or in vacuum down to 10⁻⁴ mm Hg.